If you're confused over who is paying for some political ads in California this campaign season, you're not alone - but you shouldn't have the same problem come next election cycle.

The state's campaign finance watchdog has approved a new rule requiring more disclosure in political advertisements aimed at a specific candidate or ballot measures, even if that ad doesn't explicitly tell you how to vote.

Previously, if a group independent of a candidate or campaign paid for an ad but didn't include words such as "vote for" or "vote against," it didn't have to say who funded them.

The Fair Political Practices Commission decided this week that more vague ads can be required to disclose their donors if a reasonable person would see it as an appeal for a vote. For example, if an ad that runs before a mayoral election says, "Support the mayor's stance against more budget cuts," it will now be subject to disclosure laws.

"This is a great day for Californians," commission Chairman Dan Schnur said of the new rule in a written statement, adding that it may be the first of its kind in the nation. "By forcing the disclosure of those who truly attempt to influence the outcome of an election, we have put an end to the most egregious of campaign tactics."

The rule will take effect in 30 days - well after California's Nov. 2 election.

The change was supported by good government groups, who argued there is more harm in hiding donors than letting voters know who is behind a certain issue or candidate.

But political attorneys fought the rule, arguing that the Fair Political Practices Commission was exceeding its authority.

Schnur said the new law will simply give voters more information.

"Now, when groups try to stay in the shadows by sending out carefully crafted campaign messages in the days and months before an election that are nothing than thinly veiled attempts to sway the electorate, the public will know who is behind them," he said.

San Francisco campaign lawyer Jim Sutton, however, questioned the legality of the change. He said the commission is going even further than the U.S. Supreme Court did in a recent case, and that the rule itself could be challenged in court.

"It's ridiculous," he said. "It's a waste of time and money and effort when there are so many more important cases out there."